The fully-integrated system operates at medium speed and offers a compact design together with ABB’s high-efficiency permanent magnet (PM) generator, which maximizes offshore performance. With 80 percent fewer active part components (which are typically large and heavy) than an equivalent 5 MW direct drive machine, the M5000 requires less maintenance and has an availability rate of more than 98 percent.

The medium speed gearbox does not need any fast-moving sections, only the slow rotating stage, which improves the system’s overall reliability, especially at over 5 MW. Together with the ABB generator/converter package, the system is fully optimized for future advanced grid code compliance.

Permanent magnet generators also have no excitation losses because magnets are used in the rotor instead of copper windings to create an excitation field. This makes the generator smaller and extremely efficient, especially with partial loads at low wind.

By the end of 2013, AREVA will have installed 120 turbines at two North Sea wind farms – Borkum West II and Global Tech I – each using ABB PM generators built specifically for offshore wind production. Along with the generators, ABB’s delivery scope also includes converters and switchgear.